254 S. SAGUCHI 



two granules, which are usually arranged in a horizontal plane. 

 Cases in which they are separated from each other or in which 

 they seem to consist of a single granule are not rare. 



If.. The gall-duct of Rana esculenta. The centrosome (fig. 57) 

 surrounded by a clear halo is situated above the nucleus and con- 

 sists of two granules, the axis of which either corresponds to the 

 cell-axis or is more or less oblique to it. 



5. The trachea of Trigonocephalus and the rat. The centrosome 

 in both these forms, is situated between the nucleus and the 

 cuticle, surrounded by a halo, just as described under 4 (fig. 69). 



6. The efferent tubule of testis of the mouse and rat. The 

 existence of centrosomes in cihated cells in the vas efferens was 

 noted by Zimmerman ('98), Henry ('00), Ach ('02), Ikeda ('06) 

 and Erhard ('10). According to Zimmerman, who has inves- 

 tigated ciliated cells of the human epididymis, the centrosome, 

 surrounded by a clear halo, is situated immediately below the 

 surface, and consists of two granules, the line of connection be- 

 tween them being either vertical or more or less oblique to the 

 cell-axis. The observations of Ikeda and Erhard are in accord 

 with those of Zimmerman. On the other hand, there is some 

 difference of opinion as to the shape and position of the centro- 

 some. In the epididymis of man, Henry found it above and near 

 the nucleus, while Ach says that it consists of one, two or three 

 granules, surrounded by a clear halo and that it lies either above 

 or by the side of the nucleus or near the cell-basis. 



In ciliated cells of the efferent tubule of the mouse and rat, 

 I have also frequently seen centrosomes, which differ consider- 

 ably in shape in the two species. 



In the mouse, the centrosome of the ciliated cell (figs.- 82, 

 86) is situated immediately below the row of basal corpuscles, 

 either in the middle or near the periphery of the cell, and con- 

 sists of two granules which are always arranged in the horizontal 

 plane. In order to distinguish them from the adjacent basal 

 corpuscles with certainty, it is necessary to examine sections 

 carried through the ciliated cell in an exactly vertical direction. 

 Furthermore, I have often noticed, at the surface of neighboring 

 cells with brush borders, a two-granulated centrosome, arranged 



